Bill Tindall, E.Tn.
I don't spend much (too little) time on shop accessories. My diamond sharpening plates lived in grocery bags, not handily I might add. With the arrival of freshly surfaced plates I was motivated to give them a home.
The plate is laid onto some scrap of wood. Strips of wood are glued around its border as seen in the 3rd to the right box half. A second scrap of wood is glued to the top (don't forget to remove the plate before adding the top ). When glue is cured saw it in half on band saw. If you forget to remove the plate saw in half very carefully with a hand saw) Oil the back of the plate to keep for rusting, drop it in the box half and seal the joint with something (I used E 6000). Done!
It is so simple I could find the time to do it. And it used up scraps way to valuable to burn(yet).